Updated measurement of the tau lepton lifetime

A new measurement of the mean lifetime of the τ lepton is presented. Three different analysis methods are applied to a sample of 90 000 τ pairs, collected in 1993 and 1994 with the ALEPHdetector at LEP. The average of this measurement and those previously published by ALEPHis ττ = 290.1 ± 1.5 ± 1.1 fs.